Synthesis gas manufacture



United f States Patent SYNTHESIS GAS MANUFACTURE Numer Martin Kapp, Swarthmore, and Frederick vWilliam Sullivan lll, Media, Pa., yassiguors to Houdry Process 4 Corporation, Wilmington, Del., a corporation of Delaware Application November 6, 1953, serial No. 390,602 'z claims. (c1. 48-196) The present invention relates to the preparation of gas mixtures, hereinafter called synthesis gas, which comprise hydrogen and carbon monoxide suitable for use in the preparation ofsynthesized hydrocarbons. It is more particularly directed to the preparation ofsynthesis gas from the reaction of normally gaseous hydrocarbons with oxygen and/or carbon dioxide donors carried by a circulating molten heat transfer material.

In co-pending application Serial No. 323,718, tiled December 2, 1952, now U. S. Patent 2,754,187, there is described a process Afor the preparation of synthesis gas by the reaction of normally gaseous hydrocarbons with alkali metal-typecarbonate's, which carbonates may be molten heat transfer agents, catalysts, oxygen donors and carbon dioxide donors at the same time. The claims of that application are directed to the reaction of the carbonate with the feed gas. The' claims of this application are directed to the feature of circulating the molten heat transfer material and the donor material for the purpose of re-heating the heat transfer material and regenerating the donor material. It will be understood that in the-process according tothisY application, the donor material and the molten heat transfer material may be the same substance or they may be separate substances.

The primary object of this invention is reduction of the cost of producing synthesis gas by the elminiation of the necessity for` producing relatively high-purity oxyge or relatively high-purity carbon dioxide.

`Another objectof this invention is the provision of process for continually and eiiiciently producing'synthesis gas from a normally gaseous hydrocarbon and a donor material. Other objects of the invention will be more readilyl apparent from the accompanying diagrams .and the detailed specication.

In general, the objects of the invention are accomplished by circulatinga molten heat transfer material and a donor material serially through a reaction chamber and a regeneration chamber. The temperature in the reaction chamber must be in the range of 1400 to 2000 F. and the molten heat transfer material must be one which is .liquid within the desired range, preferably within the entire range.

Broadly the donor must be one which is capable of donating pure oxygen or pure carbon dioxide to gaseous hydrocarbons within the specified temperature range. It must also be capable of being rapidly regenerated on contact with an impure source of oxygen or carbon dioxide, as the case may be. Oxygen donors found particularly useful in practicing this invention are stannic oxide, antimony trioxide, and ferric oxide. Carbon dioxide' donors found particularly useful in practicing this invention are sodium carbonate, potassium carbonate and barium carbonate.

A list of molten heat transfer agents found suitable for use in this invention is set forth in the following table:

ice,

In addition, various mixtures of the above-mentioned metals and compounds or other suitable mixtures, such as eutectic mixtures involving other metals or compounds maybe employed.

lt will be understood that while the molten heat carrier must always be in a liquid state, the donorcan be a liquid or a finely divided solid, suspended or slurried in the carrier. Not only must the heat transfer agent be molten, but-it must have sufficient iluidity to permit easy ow. On the other hand, both the donor and the heat ltransfer agent must be of low enough volatility to avoid substantial evaporation or sublimation losses during operation at temperatures in the range of 1400 to 2000 F. Any catalytic agent which maybe employed will usuallly meet requirements similar to those applying to the donor agents. n l

Regeneration is accomplished by intimately contacting the donor material with a regeneration gas. The gas may be rich in CO2 if a carbonate is used as a donor material or rich in'oxygen if a reducible metal oxide is used. Air is thegpreferred regeneration gas for the reducible metal oxides. Flue gases from the air oxidation of anycarbonaceous material or normally gaseous hydrocarbon make a very satisfactory regeneration gas for the carbonate donors. In the preferred method according to this invention,`regeneration gas is simply bubbled through thedonor-carrying molten heat transfer agent.

The lreactions of this invention vary, depending on what type of` donor is'used. Where a reducible metal Oxide' is 'used as an oxygen donor, the chemical reactions-maybe:`

(l) Reaction chamber- Y u y;MO-{CH4 MICO-l-2H2 (2)' Regeneration chamber- Where M is the metal of any reducible metal oxide, nl is the subscript value obtained by dividing the valence of oxygen by the valence of M and the methane may be substituted in whole or in part by any other normally gaseous hydrocarbons.

Where the donor is a carbonate, the chemical reactions may be:

( l) Reaction chamber- MCO3+CH4 MO-|-2CO+2H2 (2) Regeneration chamber- MnO-l-COz-e M,',CO3

Where M represents an alkali metal or an alkaline earth metal, n is the subscript value obtained bydividing the valence of oxygen by the valence of M, and the methane may be substituted in Whole or in part by other normally gaseous hydrocarbons.

In addition to the type of operation set forth immediately above, it is possible to` vary the hydrogen and carbon monoxide ratios by introducing to the reactor controlled amounts of steam. For example, a reaction of the following nature results in a dilerent hydrogen to carbon monoxide ratio than the reaction set forth above.

By changing the steam-hydrocarbon ratio of the charge gas, the hydrogen to carbon monoxide ratios in the product can be regulated to an appreciable extent. This is of definite advantage in synthesis operations wherein the requirements of the charge stock include specific hydrogen to carbon monoxide ratios which can be met as described above.

The diagrammatic sketch in Figure 1 illustrates a typical system found useful in practicing this invention. The system includes a reactor 12 and a regenerator 14 having al heat transfer agent circulation Vsystem as lettered on the drawing. Heat economizers and 11 preheat the feed gas and the regeneration gas by cooling the synthesis gas from the reactor and ue-gas from the regenerator respectively. Feed gas is urged through the economizer 10 and the reactor under pressure. Regeneration gas is forced through economizer 11 by pumps 1S and 16, the gas from the former serving as the motivating force of a gas lift and the latter serving as the primary source of regeneration gas. Y

Typical examples of the process of this invention are as follows:

Example l Methane is preheated to about 1000o F. in economizer 10 from which it is fed to reactor 12, about 18 feet in diameter, which contains molten tin and stannic oxide at a temperature of about 1700 F. The methane reacts with the stannic oxide to form synthesis gas. 'Ihe high temperature of the synthesis gas is utilized in economizer 10 to preheat incoming methane.

The regenerator 14 is about 24 feet in diameter and is heated to about l800 F. Air fed through economizer 11 is preheated to about 1000" F. The air from pump 16 is bubbled upwardly through the molten tin from the bottom of the regenerator to form stannic oxide. The air from pump is passed through an eductor 18 for gas lifting molten tin from a level below the reactor to the upper part of the regenerator. This air also helps oxidize the tin. Flue gas, taken off from the regenerator at about l800 F. is flowed through economizer 11` for pre-heating air.

In this example, for each cubic foot of methane fed, 3 cubic feet of synthesis gas are produced, and for each 3 cubic feet of synthesis gas produced, 2.88 cubic feet of air are required for regenerating the stannic oxide.

4 Example Il Molten barium chloride is used as a heat transfer medium in place of the molten tin of Example I; barium carbonate, a carbon dioxide donor, replaces the stannic oxide of Example I; and flue gas from burning methane is used as a regenerating gas in place of the air of Example I.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. In the method of continuously producing synthesis gas by the reaction of a normally gaseous hydrocarbon with a reducible metal oxide donor material to form as gaseous products CO and H2, the improvement which comprises circulating said metal oxide donor material in admixture with an insert inorganic molten heat transfer agent through a reaction zone while at a temperature in the range of l4002000 F., passing such normally gaseous hydrocarbon at a temperature below that of said molten agent into said admixture injsaid reaction zone to eifect reaction between said donor material and said hydrocarbon with reduction of said donor material to lower valence state, withdrawing from said reaction zone molten heat transfer agent containing said donor material in lower valence state and passing the withdrawn admixture to a reheatingand regenerating zone, contacting said last-mentioned admixturein said last-mentioned zone with heated oxygen-containing gas to restore said donor material to its original metal oxide form while simultaneously effecting reheating of the heat transfer agent, returning said restored donor material and said reheated transfer agent to said reaction zone, and continuously withdrawing gaseous products from said reaction zone. 2. The method in accordance with claim 1 wherein said oxygen-containing gas is air, said molten heat transfer agent is tin and said ldonor material is stannic oxide.

References Cited in the file of this patent I UNITED STATES PATENTS 1,943,821 Hanks et al. Ian. 16, 1934 2,449,359 Abrams et al Sept. 14, 1948 2,513,994 Davidson .luly 4, 1950 2,602,809 Dickinson July 8, 1952 2,671,719 Lewis Mar. 9, 1954 2,671,720 Lewis etal. Mar. 9, 1954 FOREIGN PATENTS i 597,221 Great Britain Ian. 21, 1948 UNITED STATES PATENT OFFICE CERTIFICATE 0F `CORRECTION Patent No. 2,844,453 July 22, 1958 Numey. Martin Kapp et al.

d that error appears in the-printed specification It is herebjr certifie on and that the said Letters of the above -numbered patent requiring correoti Patent should read as corrected below.

f Column 4, line 19, for ."insertu read inert Signed and sealed this 21st day of October 1958.

(SEAL) Attest: KARL H..AXLTNE ROBERT C. WATSON Commissioner of Patents Attesting Oficer 

1. IN THE METHOD OF CONTINUOUSLY PRODUCING SYNTHESIS GAS BY THE REACTION OF A NORMALLY GASEOUS HYDROCARBON WITH A REDUCIBLE METAL OXIDE DONOR MATERIAL TO FORM AS GASEOUS PRODUCTS CO AND H2, THE IMRPOVEMENT WHICH COMPRISES CIRCULATING SAID METAL OXIDE DONOR MATERIAL IN ADMIXTURE WITH AN INSERT INORGANIC MOLTEN HEAT TRANSFER AGENT THROUGH A REACTION ZONE WHILE AT A TEMPERATURE IN THE RANGE OF 1400-2000*F., PASSING SUCH NORMALLY GASEOUS HYDROCARBON AT A TEMPERATURE BELOW THAT OF SAID MOLTEN AGENT INTO SAID ADMIXTURE IN SAID REACTION ZONE TO EFFECT REACTION BETWEEN SAID DONOR MATERIAL AND SAID HYDROCARBON WITH REDUCTION OF SAID DONOR MATERIAL TO 